“Captain Horst!” said Jensen, with sternly level authority. “Be good enough to sit down and remain quiet. All matters relating to the _Gloucester City_ come within my province.” Horst, his arms up as though to guard himself, went slowly backward to his seat but did not sit. There was madness in his eyes. “How could they know?” he said to himself in a sharp-breathed whisper, “--_the exact words!_----” “What do you mean?” queried Lyngstrand, curiously. Horst replied without thinking, more to himself than to his questioner. “The exact words of her call for help--a year ago! My wireless picked it up after we had left her----” He stopped suddenly, realized that he had betrayed himself. “Then----!” cried Lyngstrand, jumping up from his seat and taking a step forward. His eyes, full of menace, searched the ex-U-boat commander’s face. “Be quiet--both of you!” commanded Jensen, holding up his hand. The regular succession of raps had commenced again. Jensen listened to them, nodded. Then he himself rapped a message in English on the table--“_who are you?_” Horst and Lyngstrand listened in dead silence as the answer spelled itself out upon the table. “_h-e-n-r-y s-m-i-t-h w-i-r-e-l-e-s-s o-p-e-r-a-t-o-r g-l-o-u-c-e-s-t-e-r c-i-t-y._” Jensen turned a glance of wonderment to his comrade. Horst, reading the message as currently as the others, looked as though about to faint. “Stop it!” he said, hoarsely. “Stop it!” Jensen ignored him, rapped again upon the table--“_where are you now?_” The answer came immediately. “_a-t y-o-u-r s-i-d-e_” The three of them sprang back simultaneously, as from the presence of a ghost. Their eyes probed empty air. Jensen spoke aloud, still in English. “Can you see us--hear us?” The raps of the invisible hand upon the table replied at once. “_y-e-s_” “_Mein Gott!_” muttered Horst. “I shall go mad!” Jensen continued his colloquy. “Where is the _Gloucester City_?” He smiled to himself as though setting a trap for this unseen intelligence. “Is she still afloat?” The raps recommenced without hesitation. “_y-o-u-r a-n-c-h-o-r f-i-x-e-d- i-n u-p-p-e-r w-o-r-k-s_” Lyngstrand uttered an ejaculation of awed astonishment. He looked to see the sweat pearling on Captain Horst’s forehead. The raps spelled out, spontaneously, an explanatory afterward. “_w-e l-e-d y-o-u t-o i-t_” “_We?_” queried Jensen. “Who are ‘_we_’?” “_t-h-e d-r-o-w-n-e-d_” The raps were decisive. “Why?” Lyngstrand admired his comrade’s steely self-control. “Why did you lead us to it?” “_h-e c-a-n g-u-e-s-s_” “Who?” “_t-h-e m-u-r-d-e-r-e-r_” Both glanced swiftly at Horst. He was speechless, his face a study in blanched terror. “_h-e k-n-o-w-s_” added the raps. There was something indefinably malicious about their sound. “Stop it!” Horst’s voice was strangled, scarcely audible. “Stop it!” Jensen was unmoved. “How many of you?” he asked. Lyngstrand, fascinated by this conversation with the unseen, was grateful for the question.